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Earth


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13,000 km
Approximate diameter of Earth.
Oblate Spheroid
Shape of the Earth?
71%
Percentage of the Earth covered in water?
23.5°
Tilt of the Earth's axis?
Nitrogen
The sky is BLUE because that part of the spectrum gets scattered by . . .
Light Pollution
Main cause of optical pollution?
Latitude
Position north or south of the Equator.
Longitude
Position east or west of the Greenwich Meridian.
Meridian
The imaginary line in the sky between the observers Pole and Zenith?
Zenith
The point in the sky directly above the observer.
Reflector
Type of telescope that collects light, 'bounces' it off a concave mirror, brought to a focus by a secondary mirror further up the tube.
Lens sagging and colour aberration.
Why are larger telescopes 'reflectors' rather than 'refractors'? Because Refractors suffer from . . .
Radio observations
What can Mobile phone signals and telecommunications affect?
Why are observatories built in the mountains?
There is less atmosphere to obscure viewing; good, dry weather; fewer clouds and remote to decrease light pollution.
Visible light, microwaves and some radio waves.
What is Earth's atmosphere transparent to?
Because that part of the spectrum gets absorbed by the Earth's atmosphere.
Why are X-Ray, infrared and ultraviolet observatories located on spacecraft?
Van Allen Belts
Name of the magnetic field around the Earth that traps solar particles.